Although considerable knowledge is available concerning the biochemistry of collagen, there is a dearth of information on the chemistry of the collagenous fibers of the peridontium. In order to alleviate this situation, studies on the chemistry of the insoluble matrix of gingiva and cementum will be performed. The tissues will be reacted with cyanogen bromide (CNBr) and the resulting peptides will be isolated and characterized. In this way a detailed biochemical characterization of the structural aspects of these collagens will be obtained, which then can be compared to that of other collagens. Preliminary observations on gingiva and cementum suggest that each contain an unusually high level of noncollagenous protein(s). The solubilization of these components will be attempted by mild, and possibly by degradative, extraction procedures, and the character of the proteins determined by usual biochemical methods. It is anticipated that these studies will add to an understanding of the mechanisms of destruction of these tissues in periodontal disease.